fix(datepicker): add asterisk when required, more unit tests

* Fixes the datepicker not getting the asterisk, when it's required and inside of a md-input-container.
* Adds missing unit tests for the md-input-container integration.

Fixes #8950.

Closes #9043

Author: crisbeto

src/components/datepicker/js/datepickerDirective.js

@@ -54,6 +54,7 @@
    * </hljs>
    *
    */
+
   function datePickerDirective($$mdSvgRegistry, $mdUtil, $mdAria) {
     return {
       template: function(tElement, tAttrs) {
@@ -121,6 +122,7 @@
         var mdDatePickerCtrl = controllers[1];
         var mdInputContainer = controllers[2];
         var parentForm = controllers[3];
+        var mdNoAsterisk = $mdUtil.parseAttributeBoolean(attr.mdNoAsterisk);
 
         mdDatePickerCtrl.configureNgModel(ngModelCtrl, mdInputContainer);
 
@@ -146,6 +148,10 @@
 
           if (!mdInputContainer.label) {
             $mdAria.expect(element, 'aria-label', attr.mdPlaceholder);
+          } else if(!mdNoAsterisk) {
+            attr.$observe('required', function(value) {
+              mdInputContainer.label.toggleClass('md-required', !!value);
+            });
           }
 
           scope.$watch(mdInputContainer.isErrorGetter || function() {

src/components/datepicker/js/datepickerDirective.spec.js

@@ -21,7 +21,7 @@ describe('md-datepicker', function() {
          'ng-disabled="isDisabled">' +
     '</md-datepicker>';
 
-  beforeEach(module('material.components.datepicker', 'ngAnimateMock'));
+  beforeEach(module('material.components.datepicker', 'material.components.input', 'ngAnimateMock'));
 
   beforeEach(inject(function($rootScope, $injector) {
     $compile = $injector.get('$compile');
@@ -115,17 +115,6 @@ describe('md-datepicker', function() {
     }).not.toThrow();
   });
 
-  it('should work inside of md-input-container', function() {
-    var template =
-        '<md-input-container>' +
-          '<md-datepicker ng-model="myDate"></md-datepicker>' +
-        '</md-input-container>';
-
-    expect(function() {
-      $compile(template)(pageScope);
-    }).not.toThrow();
-  });
-
   describe('ngMessages support', function() {
     it('should set the `required` $error flag', function() {
       pageScope.isRequired = true;
@@ -623,4 +612,68 @@ describe('md-datepicker', function() {
       expect(element.querySelector(triangleSelector)).toBeNull();
     });
   });
+
+  describe('md-input-container integration', function() {
+    var element;
+
+    it('should register the element with the mdInputContainer controller', function() {
+      compileElement();
+
+      var inputContainer = element.controller('mdInputContainer');
+
+      expect(inputContainer.input[0]).toBe(element[0].querySelector('md-datepicker'));
+      expect(inputContainer.element).toHaveClass('_md-datepicker-floating-label');
+    });
+
+    it('should notify the input container that the element has a placeholder', function() {
+      compileElement('md-placeholder="Enter a date"');
+      expect(element).toHaveClass('md-input-has-placeholder');
+    });
+
+    it('should add the asterisk if the element is required', function() {
+      compileElement('ng-required="isRequired"');
+      var label = element.find('label');
+
+      expect(label).not.toHaveClass('md-required');
+      pageScope.$apply('isRequired = true');
+      expect(label).toHaveClass('md-required');
+    });
+
+    it('should not add the asterisk if the element has md-no-asterisk', function() {
+      compileElement('required md-no-asterisk');
+      expect(element.find('label')).not.toHaveClass('md-required');
+    });
+
+    it('should pass the error state to the input container', inject(function($material) {
+      compileElement('required');
+
+      var ngModelCtrl = element.find('md-datepicker').controller('ngModel');
+      var invalidClass = 'md-input-invalid';
+
+      expect(ngModelCtrl.$valid).toBe(true);
+      expect(element).not.toHaveClass(invalidClass);
+
+      ngModelCtrl.$setViewValue(null);
+      ngModelCtrl.$setTouched(true);
+      $material.flushOutstandingAnimations();
+
+      expect(ngModelCtrl.$valid).toBe(false);
+      expect(element).toHaveClass(invalidClass);
+    }));
+
+    afterEach(function() {
+      element.remove();
+    });
+
+    function compileElement(attrs) {
+      var template =
+        '<md-input-container>' +
+          '<label>Enter a date</label>' +
+          '<md-datepicker ng-model="myDate" ' + attrs + '></md-datepicker>' +
+        '</md-input-container>';
+
+      element = $compile(template)(pageScope);
+      pageScope.$digest();
+    }
+  });
 });